fix(timeline): clear multi-select on drag start and lock in SSE edge-case coverage

- useTimelineDrag: onProjectBarMouseDown and single-alloc drag path now reset
  multiSelectRef + multiSelectState before starting a new drag, so the
  FloatingActionBar is dismissed immediately when an unrelated drag begins
- FloatingActionBar.test.tsx: 4 regression tests for the null-render guard
  (count=0) and all three label variants
- useTimelineSSE.test.ts: 2 new tests — tab hides during pending reconnect
  timer (clears timer, resyncs on next open) and first-ever connection fails
  before any open (retry open still resyncs correctly)
- assistant-tools-user-admin-inventory-read.test.ts: add isActive to expected
  findMany select shape (already in production, test was stale)

Co-Authored-By: claude-flow <ruv@ruv.net>

apps/web/src/components/timeline/FloatingActionBar.test.tsx

@@ -0,0 +1,64 @@
+import React from "react";
+import { renderToStaticMarkup } from "react-dom/server";
+import { describe, expect, it, vi } from "vitest";
+import { FloatingActionBar } from "./FloatingActionBar.js";
+
+const noop = vi.fn();
+
+describe("FloatingActionBar", () => {
+  it("renders nothing when no items are selected", () => {
+    const html = renderToStaticMarkup(
+      <FloatingActionBar
+        selectedAllocationCount={0}
+        selectedResourceCount={0}
+        onDelete={noop}
+        onAssign={noop}
+        onClear={noop}
+        isDeleting={false}
+      />,
+    );
+    expect(html).toBe("");
+  });
+
+  it("shows allocation count label when allocations are selected", () => {
+    const html = renderToStaticMarkup(
+      <FloatingActionBar
+        selectedAllocationCount={2}
+        selectedResourceCount={0}
+        onDelete={noop}
+        onAssign={noop}
+        onClear={noop}
+        isDeleting={false}
+      />,
+    );
+    expect(html).toMatch(/2 allocations selected/i);
+  });
+
+  it("shows resource count label when resources are selected", () => {
+    const html = renderToStaticMarkup(
+      <FloatingActionBar
+        selectedAllocationCount={0}
+        selectedResourceCount={1}
+        onDelete={noop}
+        onAssign={noop}
+        onClear={noop}
+        isDeleting={false}
+      />,
+    );
+    expect(html).toMatch(/1 resource selected/i);
+  });
+
+  it("shows combined label when both allocations and resources are selected", () => {
+    const html = renderToStaticMarkup(
+      <FloatingActionBar
+        selectedAllocationCount={1}
+        selectedResourceCount={1}
+        onDelete={noop}
+        onAssign={noop}
+        onClear={noop}
+        isDeleting={false}
+      />,
+    );
+    expect(html).toMatch(/1 allocation.*1 resource/i);
+  });
+});

apps/web/src/components/timeline/FloatingActionBar.tsx

@@ -1,5 +1,6 @@
 "use client";
 
+import React from "react";
 import { clsx } from "clsx";
 
 interface FloatingActionBarProps {